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Estimation of sediment trapping behind check dams using high-density electrical resistivity tomography

Fang, N.F., Zeng, Y., Ni, L.S., Shi, Z.H.
Journal of hydrology 2019 v.568 pp. 1007-1016
bedload, bulk density, electrical resistance, electrodes, geometry, least squares, sediment deposition, sediment transport, sediment traps, sediments, tomography, watersheds, China
Check dams are very important structures for torrent control areas throughout the world. Measuring the sediment deposition behind check dams is thought to be an effective method of estimating the sediment yield of small catchments. In this study, we employed a high-density electrical resistivity system to detect sediment at six check dams distributed in the hilly and gully area of the Loess Plateau. A total of 11 lines were arranged, with 60 electrodes along each line. The resultant resistivity data were inverted into subsurface structures using least-squares inversion techniques. The results indicate that the sediment bottom can been identified using an electrical resistivity contour method. Using trenches, boreholes and drillings to calibrate the calculated values, the accuracy of the high-density electrical resistivity tomography method was found to be quite high (95.7%). The bulk density increases with the sediment deposit depth and can reach a maximum of 1.6 g cm−3. Geometric methods considering three shapes (V-shaped, U-shaped and trapezoidal) were used to estimate the profile area of the check dams; the V-shaped geometric method showed high accuracy. This study provides a four-step approach based on high-density electrical resistivity tomography and a geometric method to estimate sediment yield for check dam-controlled catchments. This methodology enables the measurement of the total sediment yield, including both the suspended and bedload sediment transport, from an ungauged catchment.